European Union officials said three cases had also been reported in the United States, adding that most infections reported outside Germany involved German nationals or people who had recently travelled to the country.[23]

On May 26, 2011, German officials stated the contaminated vegetables were organic cucumbers that originated in Spain, but European Union spokesperson on 30 May said that two Spanish greenhouses, that were suspected to be sources, had been closed and were being investigated.[10] The investigation included analyzing soil and water samples from the greenhouses in question, located in the Andalusia region, with results expected by 1 June.[24] Cucumber samples from the Andalusian greenhouses did not show E. coli contamination[25][26], but a cross-contamination during transport in Germany or distribution in Hamburg are not discarded.[27]

On May 31, an EU official said that the transport chain was so long that the cucumbers from Spain could have been contaminated at any point that occurred along the transit route.[21]Spanish officials, said before that there was no proof that the outbreak originated in Spain; Spanish Secretary of State for European Affairs Diego Garrido said that "you can't attribute the origin of this sickness to Spain."[10].

On Tuesday 31 May, lab tests showed that two of the four cucumbers examined did contain toxin-producing E. coli strains, but not the O104 strain that was found in patients; this means that Spanish cucumbers are not the source of the outbreak and German authorities have to start all over again in their search for the source. The bacteria in the other two cucumbers have not yet been identified. No other possibilities have been officially proposed. Paul Hunter, professor of health protection at the University of East Anglia located in Norwich, United Kingdom, pointed out that salads are a regular cause of outbreaks of food borne diseases including STEC, like this one, and Salmonella.[23] As of the first of June, the source is still unknown.[23]

The German government warned against the consumption of all raw cucumbers, tomatoes and lettuce.[30]

In response to the outbreak, several countries implemented restrictions or bans on the import of produce. Belgium banned imports of Spanish cucumbers on May 31,[18]Austria banned imports of Spanish cucumbers, tomatoes and aubergines, and the Czech Republic recalled all Spanish cucumbers on sale on May 30.[31]

On 30 May, the Spanish government said that it was considering requesting compensation from Germany, claiming that "tremendous damage" had been done to the country's agricultural sector as a result of reduced exports stemming from the incompetent way Germany handled the outbreak.[32] Since the beginning of the crisis, farms in the Andalusian region were estimated to have lost up to eight million euros per day.[33] Spanish Health Minister Leire Pajin firmly stated there were no native cases in Spain by May 31.[21]

By May 31, The Dutch Food and Wares Authority spokeswoman Marian Bestelink, said that investigations made of the business run by the local Dutch cucumber grower and Dutch warehouse did not uncover any traces of the bacteria at that time. [21] The Netherlands had also stopped exporting cucumbers to Germany on May 31.[18]

On May 31st, Austrian authorities inspected 33 organic supermarkets to make sure Spanish vegetables had been removed. The move came after an apparently overzealous recall and ban on sales of both cucumbers, tomatoes s and aubergines (eggplants) that had originated in Spain and were delivered to Austrian food stores by various German companies. [21]

The Czech Government officials said that their labs had tested a total 120 potentially tainted Spanish cucumbers the 29th as an interim safety measure, but refused to cast blame for the outbreak, which had yet to reach the Czech Republic by that date. [21]

On May 31, a World Health Organization food safety expert, Hilde Kruse, said "Almost all cases being reported in other countries have a link to travel or residence in Germany" and indicated that Germany was still the most infected country so far. [21]